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N0; 6l9,662. Patented Feb. I4, I899;

D. M. BLISS.

TELEPHDNE SIGNALING SYSTEM.

(Application filed Apr. 11, 1898.)

(No Model.)

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UNITED STATES PATENT @FFICE.

DONALD M. BLISS, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO THE HOLTZER-CABOT ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE SIGNALING SYSTEM.

SPECIFICATION forming part of Letters Patent No. 619,662, dated February 14, 1899,

Application filed April 1 1, 1 8 9 8.

T0 aZZ whom it may concern:

Be it known that I, DONALD M. BLISS, of Brookline, county of Norfolk, and State of Massachusetts, have invented an Improvement in Telephone Signaling Systems, of which the following description, in connection with the accompanying drawings, is a specification, like letters and figures on the drawings representing like parts.

The present invention relates to a telephone signaling system, and is embodied in a system of that class in which a number of stations are arranged in a single circuit and in which it is desirable to sound an audible signal at each station by the operation of a generator at any station. In a system of this kind, however, if the call-bell magnets are all in series with the main line it has been found that poor results are obtained owing to the resistance and self-induction of the magnets, and it has been proposed, therefore, to arrange the call-bells in multiple, each call-bell magnet being in a branch extending across from one side of the circuit to the other. In arranging such a system, however, when there are a number of stations it is necessary to wind the call-bell magnets to a high degree of ohmic resistance in order that the current may be distributed throughout the system, so that it is not only difficult to obtain current enough from the generator to properly operate all the call-bells, but it is also impracticable to Wind the call-bell magnets so as to obtain the best results. In accordance with the present invention these dificulties are obviated by arranging each generator and call-bell in a local circuit entirely and permanently disconnected from the telephone-circuit, each local circuit being in series with the coarse or lowresistance Winding of a transformer, the fine or high-resistance winding of which extends from one side to the other of the telephone-circuit. Owing to the high self-induction of a transformer the coils which extend from one side to the other of the telephone-circuit may afford sufficient impedance and yet have an ohmic resistance which is low compared with that which would be required in the bell-magnets if they were connected across the circuit. In this system when the generator at any station is operated Serial No. 677,155. (No modem a current is induced in the secondary of the transformer at the said station and a current is induced in the coarse winding of the transformers at each station, there being sufficient impedance in each of the high-resistance windings to insure the distribution of current throughout the entire system without the generation of an abnormally large current, while the call-bells may be of the usuallowresistance type and free from the objections encountered in the use of the high-resistance bell-magnets which have to be employed where the magnets are connected in a line extending across the main circuit.

Figure 1 is a diagram view of a telephone signaling system having four stations; and Fig. 2 is a similar View of the signaling system at one station, showing a modification in the circuit.

The generator a, which is usually of the magneto type, and the call-bell b are shown as included in a local circuit 0 d, in which is also included the coarse or low-resistance winding 6 of a transformer c e, the high-resistance winding 6 of which is connected across the main circuit at y. The construction being the same at each of any desired number of stations, it will be seen that the operation of any generator will produce in the local circuit a current of comparatively low potential, which will induce in the high-resistance winding of the transformer a current of comparatively high potential, which is transmitted through the main circuit cc y and through the high-resistance coil of each transformer, the transformer operating in this case as a step-down transformer to induce a current of comparatively low potential in the low-resistance local circuit to operate the bell.

As shown in Fig. 1, the bell b is in multiple with the generator at, being connected across the circuit 0 d by means of conductors b and the generator is shown as provided with a switch or circuit-closer a which normally stands open, but is adapted to be closed, as by a finger-piece or button a when the generator is in use. It is obvious, however, that a switch of any suitable construction and arrangement may be utilized for the purpose.

The bell and generator may equally well be arranged in series, as shown in Fig. 2, and in this instance the current may in each instance pass through the generator-coils, which are of comparatively low resistance, or may, as shown, pass through a shunt-circuit a provided with a normally-closed switch a adapted to be opened when the generator is in use, as by means of the finger-piece (0 The telephone instruments may be of the usual type and included in the circuit in the usual Way, and are not herein shown, since they form no part of the present invention, which may be readily understood without including this part of the system.

It will be seen from the foregoing descrip tion that the main circuit is clear and free from disturbance when in use as a telephonecircuit, the system thus being free from the objections to a system in which the audible signals are in series with the main circuit. Furthermore, the call-bells or audible signals may be of the usual type,having low-resistance magnets, and are capable of being efiiciently operated throughout a circuit havinga large number of stations, it not being necessary to provide the signals with magnets of unusually high resistance, as would be the case if the said magnets were included in branch circuits between the two sides of the main telephone-circuit.

In Fig. 1 four stations are indicated on the circuit and marked, respectively, 1, 2, 3, and 4,

the circuits at stations 1 and 4 being shown in diagram, while stations 2 and 3 are conventionally indicated by circles. There may of course be any number of stations in a circuit, and said stations are at a distance from each other.

I claim i l. A telephone signaling system comprisin g a local circuit at each station permanently disconnected from the main circuit, electromagnetic signaling mechanism in each local circuit, and a transformer at each station, said transformer having one of its coils in series with said local circuit and its other coil bridging the main circuit, substantially as described.

2. In a telephone signaling system, the combination with the main circuit, of a local circuit at each station permanently disconnected from the said main circuit, an electromagnetic signal-receiving device and generator in each local circuit, and a transformer at each station having its low-resistance coil in series with the local circuit, and its high-resistance coil bridging the main circuit, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

DONALD M. BLISS.

Witnesses:

H. J. LIVERMORE, NaNoY P. Fol-w. 

